Like Zynq the Altera drivers compile fine on x86 and others too,
so make it easier to compile test this stuff.

A10 requires REGMAP_MMIO to compile, so be explicit rather than
relying on it via ARCH_SOCFPGA.
Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Acked-by: Alan Tull <atull@opensource.altera.com>